1. Field of the Invention
This invention relates generally to the field of mobile and wireless communication systems. More particularly, the invention relates to an improved system and method for disabling a wireless device over cellular control channels.
2. Description of the Related Art
A typical cellular network is illustrated in FIG. 1. Some of the primary components include a group of mobile switching centers 110, 115 (hereinafter xe2x80x9cMSCsxe2x80x9d); a series of base stations 140-142 and 150-151; and one or more a mobile units 130. Each mobile unit 130 includes an RF module (not shown) for transmitting and receiving cellular signals. The MSCs 110, 115 communicate across an interface 150 to one or more additional networks 120 (e.g., the public switched telephone network).
The mobile station 130 contains a radio frequency (xe2x80x9cRFxe2x80x9d) module (not shown) which allows the mobile station 130 to tune to a particular frequency as designated by the cellular network. The xe2x80x9ccellxe2x80x9d site is defined by the area (e.g., line 170 in FIG. 1) surrounding each individual base station 140. In operation, each base station 140-142; 150-151 acts as an interface between the MSCs 110, 115 and the mobile stations 130; transmitting and receiving control and voice signals to and from each, respectively.
The MSCs 110, 115 perform the primary control functions for the cellular network, routing calls between the base stations 140-142; 150-151 and other networks 120 and performing a variety of call management operations (e.g., performing testing and diagnostics; monitoring network traffic . . . etc). Two databases are maintained at the MSCs 110, 115 for tracking cellular subscribers: the home location register (hereinafter xe2x80x9cHLRxe2x80x9d) and the visitor location register (hereinafter xe2x80x9cVLR xe2x80x9d).
Every cellular customer belongs to one HLR, which is associated with a particular network provider. Information relating to the customer""s account (e.g., subscribed services, account payments) is stored in the HLR along with customer tracking information which identifies the customer""s location within the overall cellular network (i.e., either within or outside of the subscribed cellular provider""s network).
The VLR keeps track of customers who are operating outside of their cellular provider""s network. For example, if MSC 110 and MSC 115 were operated by different service providers and mobile station 130 moved outside of a MSC 110""s range (where he was a subscribed) and into MSC 115""s range, then MSC 115 would open a VLR entry for the mobile station 130 and would notify MSC 110 (which would then update the HLR for the mobile station 130).
The communication interface between a mobile station 130 and a base station 140 can be broken down into two pairs of channels as illustrated in FIG. 2: a pair of voice channels and a pair of control channels. The two voice channels, the reverse voice channel (RVCxe2x80x9d) 210 and the forward voice channel (xe2x80x9cFVCxe2x80x9d) 220 carry digital or analog voice signals to and from the mobile station, respectively. The two control channels, the reverse control channel (xe2x80x9cRECCxe2x80x9d) 230 and the forward control channel (xe2x80x9cFOCCxe2x80x9d) 240 carry control signals (e.g., the number to dial, the paging signal indicating an incoming call . . . etc) to and from the mobile station 130, respectively. When the voice channels are not in operation, the mobile station 130 must continually monitor it""s designated control channels for event triggers.
Each cellular service provider broadcasts a unique System Identification Number (hereinafter xe2x80x9cSIDxe2x80x9d) on its FOCC within the cellular provider""s allocated frequency range. Accordingly, a properly equipped cellular telephone can determine which service company is providing service on a given channel by identifying the SID. Usually the SID contains three digits.
At least two identification numbers may be associated with each mobile cellular device: an electronic serial number (xe2x80x9cESNxe2x80x9d) and a mobile identification number (xe2x80x9cMINxe2x80x9d). The ESN is a 32-bit binary number which is set up by the manufacturer at the time of production. It is comprised of a manufacturer code and a serial number. The ESN is typically burned into memory (e.g., ROM) so that circuitry providing the number is secure.
The MIN is a 34-bit number that is derived from 10-digit telephone number of the mobile station. The MIN is comprised of MIN1, 24-bits which correspond to is the station""s 7-digit directory number, and MIN2, 10 bits that correspond to the station""s 3-digit area code.
The assignee of the present application has developed proprietary, two-way, wireless data communications technologies in which data packets known as Remote Access Application Messages (xe2x80x9cRAAMxe2x80x9d(trademark)) or Control Channel Application Data (xe2x80x9cCCADxe2x80x9d(trademark)) are transmitted over cellular control channels to and from cellular RF modules. See, e.g., U.S. Pat. No. 5,845,203 which is assigned to the assignee of the present application. These data packets enable a variety of new applications beyond traditional cellular voice communications, including monitoring and control of remote devices. These new systems operate completely within, and are transparent to, current established cellular networks, without usurping or compromising the voice-based infrastructure and revenue generation.
Occasionally, a mobile device employing elements of the foregoing technology must be disabled for one reason or another. Under certain conditions, the cellular device should be completely disabled such that it needs to be taken back to the factory before it will function properly again (e.g., car theft applications). In other instances, however, it would be more useful to temporarily disable the device such that it may be enabled locally and/or remotely (or otherwise disabled in a less-severe manner).
Accordingly, what is needed is a system and method for disabling a cellular device using different disabling techniques. What is also needed is a system and method for disabling a cellular device in which the manner in which the device is disabled is based on the application for which the device is employed and/or the underlying facts associated with the act of disabling (e.g., why the device was disabled).
A method is described for disabling a cellular control module comprising: disabling the cellular control module responsive to either a temporary disable command or a factory disable command received over a cellular control channel; and enabling the cellular control module responsive to an enable command received over the cellular control channel if the cellular control module was disabled by a temporary disable command but not if the cellular control module was disabled by a factory disable command.
Also described is a cellular control module for receiving commands over a cellular control channel comprising: temporary disable logic which disables the cellular control module responsive to a temporary disable command received over the cellular control channel; factory disable logic which disables the cellular control module responsive to a factory disable command received over the cellular control channel; and enable logic which enables the cellular control module responsive to an enable command received over the cellular control channel if the cellular control module was disabled by the temporary disable logic but not if the cellular control module was disabled by the factory disable logic.